Here's another way to look at it all.
This focuses on the number of matches overall which is a risky gamble for an event. Guessing how many matches you'll be able to do before you've started and found what problems teams and the field will have is a real challenge.
Code:
------------------------------- # teams ---- # matches ---- Matches/team
Overall Averages --------------- 39 ----------- 79 ----------- 10
Greater Kansas City Regional-- 60 ---------- 99 ---------- 10
Los Angeles Regional ---------- 58 ---------- 97 ---------- 10
Microsoft Seattle Regional ----- 64 ---------- 96 ----------- 9
Arizona Regional -------------- 56 ---------- 94 ---------- 10
Autodesk Oregon Regional ---- 61 ---------- 92 ----------- 9
New Jersey Regional ---------- 61 ---------- 92 ----------- 9
Chesapeake Regional ---------- 50 ---------- 92 ---------- 11
Oklahoma Regional ------------ 55 ---------- 92 ---------- 10
Buckeye Regional ------------- 60 ---------- 90 ----------- 9
Washington DC Regional ------ 59 ---------- 89 ----------- 9
Florida Regional --------------- 53 ---------- 89 ---------- 10
SBPLI Long Island Regional --- 48 ---------- 88 ---------- 11
Wisconsin Regional ------------ 50 ---------- 84 ---------- 10
New York City Regional ------ 64 ---------- 84 ----------- 8
Silicon Valley Regional -------- 50 ---------- 84 ---------- 10
San Diego Regional ----------- 49 ---------- 82 ---------- 10
Peachtree Regional ------------ 50 ---------- 82 ---------- 10
Virginia Regional -------------- 63 ---------- 82 ----------- 8
West Michigan District -------- 41 ---------- 82 ---------- 12
BAE Granite State Regional --- 48 ---------- 80 ---------- 10
Ann Arbor District ------------ 40 ---------- 80 ---------- 12
Boston Regional -------------- 53 ---------- 80 ----------- 9
Troy District ------------------ 40 ---------- 80 ---------- 12
Dallas Regional -------------- 53 ----------- 78 ----------- 9
Traverse City District --------- 38 ---------- 76 ---------- 12
Detroit District --------------- 38 ---------- 76 ---------- 12
Finger Lakes Regional ------- 44 ---------- 74 ---------- 10
Kettering District ------------ 40 ---------- 74 ---------- 11
Cass Tech District ----------- 40 ---------- 72 ---------- 11
Boilermaker Regional -------- 39 ---------- 72 ---------- 11
Midwest Regional ----------- 42 ---------- 70 ---------- 10
St. Louis Regional ----------- 35 ---------- 70 ---------- 12
Philadelphia Regional -------- 44 ---------- 66 ----------- 9
Palmetto Regional ----------- 34 ---------- 63 ---------- 11
Pittsburgh Regional ---------- 31 ---------- 62 ---------- 12
Bayou Regional ------------- 38 ---------- 60 ----------- 9
WPI Regional --------------- 29 ---------- 58 ---------- 12
Hawaii Regional ------------ 28 ----------- 56 ---------- 12
Utah Regional -------------- 33 ----------- 55 ---------- 10
Waterloo Regional --------- 30 ----------- 55 ---------- 11
Colorado Regional --------- 41 ------------- 45 ------------ 7 (incomplete)
Israel Regional -------------- 55 ------------- 27 ------------ 3 (unusual circumstances)